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United States Patent |
5,235,940
|
Nakatani
|
August 17, 1993
|
Engine valve driving apparatus
Abstract
The invention discloses a valve driving apparatus for use of an engine
including an intake valve for opening and closing an intake port, an
exhaust valve for opening and closing an exhaust port, and intake and
exhaust cam shafts for driving the intake and exhaust valves respectively,
at least one of the intake and exhaust valves being adapted to be driven
by a cam shaft located on the other side with respect thereto.
Inventors:
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Nakatani; Shuichi (Hiroshima, JP)
|
Assignee:
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Mazda Motor Corporation (Hiroshima, JP)
|
Appl. No.:
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002345 |
Filed:
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January 6, 1993 |
Foreign Application Priority Data
Current U.S. Class: |
123/90.16; 123/90.23; 123/90.27 |
Intern'l Class: |
F01L 001/34 |
Field of Search: |
123/90.15,90.16,90.22,90.23,90.27,90.39
|
References Cited
U.S. Patent Documents
4561391 | Dec., 1985 | Simko | 123/90.
|
4638774 | Jan., 1987 | Aoi | 123/90.
|
4649874 | Mar., 1987 | Sonoda et al. | 123/90.
|
4662323 | May., 1987 | Moriya | 123/90.
|
4883027 | Nov., 1989 | Oikawa et al. | 123/90.
|
4905639 | Mar., 1990 | Konno | 123/90.
|
5042438 | Aug., 1991 | Heil | 123/90.
|
5070824 | Dec., 1991 | Morishita | 123/90.
|
5184579 | Feb., 1993 | Fujiwara | 123/90.
|
Foreign Patent Documents |
62-154210 | Sep., 1987 | JP.
| |
63-117109 | May., 1988 | JP.
| |
Primary Examiner: Cross; E. Rollins
Assistant Examiner: Lo; Weilun
Attorney, Agent or Firm: Keck, Mahin & Cate
Claims
What is claimed is:
1. A valve driving apparatus of an engine comprising:
a plurality of intake valves for opening and closing intake ports;
a plurality of exhaust valves for opening and closing exhaust ports;
intake and exhaust cam shafts for driving said intake and exhaust valves;
and
at least one of said intake and exhaust valves being adapted to be driven
by a cam shaft located on a side of the valve driving apparatus opposite
to the at least one of said intake and exhaust valves.
2. A valve driving apparatus of an engine comprising:
intake valves for opening and closing intake ports of the engine;
exhaust valves for opening and closing exhaust ports of the engine;
one of said intake and exhaust valves being a three valve configuration,
the other being a two valve configuration;
any two valves of said three valve configuration being separately driven by
valve driving systems;
all valves of said two valve configuration being driven by a common valve
driving system;
a remaining valve of said three valve configuration being driven by a cam
shaft driving the two valve configuration.
3. A valve driving apparatus in accordance with claim 2, wherein said
remaining valve of the three valve configuration is positioned at an end
of the three valve configuration such that said remaining valve is spaced
far away from a center of a cylinder bore.
4. A valve driving apparatus in accordance with claim 3, wherein said
remaining valve of the three valve configuration comprises a valve having
constant valve timing and valve lift regardless of engine driving state.
5. A valve driving apparatus in accordance with claim 2, wherein said
intake valves comprise the three valve configuration and said exhaust
valves comprise the two valve configuration.
6. A valve driving apparatus in accordance with claim 2, wherein said
remaining valve of the three valve configuration is positioned such that
an upper end of a valve stem thereof is disposed closer than upper ends of
valve stems of the other two valves of the three valve configuration to
said two valve configuration.
7. A valve driving apparatus in accordance with claim 2, wherein any two
valves of the three valves configuration have valve stems having different
inclination angle.
Description
BACKGROUND OF THE INVENTION
The invention relates to a valve driving apparatus for use of an engine,
including a plurality of intake valves driven via a swing arm by intake
cams provided on an intake cam shaft and a plurality of exhaust valves
driven via a swing arm by exhaust cams provided on an exhaust cam shaft.
For instance, the invention can apply to a five-valves engine having three
intake valves and two exhaust valves.
RELATED ART STATEMENT
A four-cycle reciprocating type engine having five valves comprising three
intake valves and two exhaust valves to enhance intake and exhaust
efficiency, follow-up ability during high speed driving and permitable
maximum revolution per minute is presently known as disclosed in Japanese
Utility Model Public Disclosure No. 62-154210.
In addition, Japanese Patent Public Disclosure No. 63-117109 discloses a
valve driving system which can adjust valve opening and closing timing of
intake and exhaust valves and valve lift according to the driving state of
an engine.
An intake cam shaft in this valve driving system is provided with two cams
each for high speed and low speed. Lifters disposed between these two cams
and upper ends of valve stems have pistons therein acting as a connector
which is hydraulically driven. The valve driving system drives intake
valves in accordance with cam profile of the high speed cam when the
piston is operated, namely during high speed so that the intake valves
open at early timing and close at late timing, and increase the valve
lift, while the valve driving system drives intake valves in accordance
with cam profile of the low speed cam when the piston is not operated,
namely during low speed so that the intake valves open at late timing and
close at early timing, and decrease valve lift. Thus, this system can vary
filling rate of air-fuel mixture to be introduced into a combustion
chamber in accordance with the driving state of an engine.
In recent years, aforementioned apparatus or system tend to be used in
combination for the purpose of increasing engine power. However, the
combination of multiple valve system and valve driving system causes the
valve driving arrangement disposed in a valve driving chamber to be
complicated and thereby the valve driving chamber tends to be larger.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a valve
driving apparatus for use of an engine having a plurality of valves for
driving intake and exhaust valves from advantageous side with respect to
valve layout to enhance valve layout allowability and make the valve
driving chamber to be compact.
A further object of the present invention is to provide a valve driving
apparatus for use of an engine having a plurality of valves capable of
increasing valve layout allowability even if a valve driving system is
provided when valve stems of the valves have different inclination angle.
It is another object of the present invention to provide a valve driving
apparatus for use of an engine having a plurality of valves capable of
increasing positioning allowability of swing arms which drive intake
and/or exhaust valves by a cam shaft located at the other side with
respect thereto.
Still another object of the invention is to provide a valve driving
apparatus for use of an engine in which one of three intake or exhaust
valves is disposed at one end of the three valves configuration and is
formed as having constant valve timing and valve lift so that swirls are
facilitated to be produced.
Yet another object of the invention is to provide a valve driving apparatus
which can be widely used for an engine having totally five valves.
A further object of the present invention is to provide a valve driving
apparatus for use of an engine in which one valve of three-valves
configuration having a valve stem having an upper end disposed closest to
the other two-valves configuration is adapted to be driven by a cam shaft
located on the same side as the two-valves configuration, such that an arm
length of a swing arm for driving said one valve can be shortened.
It is still another object of the present invention to provide a valve
driving apparatus for use of an engine in which any two valves of the
three-valves configuration have different inclination angle such that
layout allowability of the valve system is increased.
In one aspect, the invention provides a valve driving apparatus for use of
an engine comprising an intake valve for opening and closing an intake
port, an exhaust valve for opening and closing an exhaust port, and intake
and exhaust cam shafts for driving the intake and exhaust valves
respectively. At least one of the intake and exhaust valves is adapted to
be driven by a cam shaft located on the other side with respect thereto.
In another aspect, the invention provides a valve driving apparatus for use
of an engine comprising intake valves for opening and closing intake ports
of the engine, and exhaust valves for opening and closing exhaust ports of
the engine. One of the intake and exhaust valves includes three valves
configuration, and the other includes two valves configuration. Any two
valves of the three valves configuration are separately driven by valve
driving systems, while all valves of the two valves configuration are
driven by a common valve driving system. A remaining valve of the three
valves configuration is driven by a cam shaft located on the other side
with respect thereto.
In a preferred embodiment of the invention, the remaining valve of the
three valves configuration is positioned at an end of the three valves
configuration such that the remaining valve is spaced far away from a
center of a cylinder bore.
In another preferred embodiment of the invention, the remaining valve of
the three valve configuration comprises a valve having constant valve
timing and valve lift regardless of driving state of the engine.
In still another preferred embodiment of the invention, the intake valves
comprise three valves configuration and the exhaust valves comprise two
valves configuration.
In yet another preferred embodiment of the invention, the remaining valve
of the three valves configuration is positioned such that an upper end of
a valve stem thereof is disposed closer to the two valves configuration
than upper ends of valve stems of the other two valves of the three valves
configuration.
In another preferred embodiment of the invention, any two valves of the
three valves configuration have valve stems having different inclination
angle.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of a valve driving apparatus for use of an
engine in accordance with the invention.
FIG. 2 is a top plan view illustrating the valve driving apparatus shown in
FIG. 1.
FIG. 3 is a top plan view illustrating the valve driving apparatus shown in
FIG. 1 with cam shafts being removed for the purpose of clarification.
FIG. 4 is a cross-sectional view of a hydraulic lash adjuster (HLA).
FIG. 5 is a schematic view illustrating a valve shifting mechanism.
FIG. 6 is a graph showing how valve timing and valve lift is controlled by
the valve shifting mechanism.
FIG. 7 is schematic view showing an area in which the valve shifting
mechanism is operated.
FIG. 8 is a block diagram for controlling the valve shifting mechanism.
FIG. 9 is a schematic view illustrating layout of intake and exhaust ports
relative to a cylinder bore and the birth of swirls.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A preferred embodiment in accordance with the invention will be explained
hereinbelow with reference to drawings.
A valve driving apparatus in accordance with the invention is illustrated
in FIGS. 1 and 2. A cylinder head 4 is secured to a cylinder block 2
having a cylinder bore 1 therein by means of four bolts 3 for each
cylinder. The cylinder head 4 is provided with three intake ports 6, 7, 8
and two exhaust ports 9, 10 each in communication with a combustion
chamber 5.
The valve driving apparatus includes an intake valve 11 for opening and
closing the intake port 6, an intake valve 12 for opening and closing the
intake port 7, an intake valve 13 for opening and closing the intake port
8, which valve 13 is overlapped with the intake valve 11 in FIG. 1, an
exhaust valve 14 for opening and closing the exhaust port 9, and an
exhaust valve 15 for opening and closing the exhaust port 10, which valve
15 is overlapped with the exhaust valve 14 in FIG. 1. Thus, the valve
driving apparatus has five valves consisting of three intake valves and
two exhaust valves.
Each valves 11 to 15 has valve stems 17 fit into valve guides 16 provided
on the cylinder head 4. Spring retainers 19 are fit into the valve stems
17 at the upper ends thereof through collets 18. Between the upper spring
retainers 19 and a lower spring retainers 20 provided on the cylinder head
4 are disposed valve springs 21.
Intake cam shaft 22 and exhaust cam shaft 23 each extending along cylinder
banks are supported by camshaft bearings 24, 25 and camshaft bearings 26,
27 respectively. The camshaft bearing 26 for the exhaust cam 23 is
disposed closer to the center of the cylinder bore 1 than the camshaft
bearing 24 facing the bearing 26, while the camshaft bearing 27 for the
exhaust camshaft 23 is disposed further spaced away from the center of the
cylinder bore 1 than the camshaft bearing 25 facing the bearing 27.
The intake camshaft 22 is provided with a cam 28 used during the engine
runs at relatively low speed and a cam 29 used during the engine runs at
relatively high speed, both cams 28 and 29 being associated with the
intake valve 11, and a cam 30 used during the engine runs at relatively
low speed and a cam 31 used during the engine runs at relatively high
speed, both cams 30 and 31 being associated with the intake valve 12,
while the exhaust valve 23 is provided with a cam 32 used during the
engine runs at relatively low speed and a cam 33 used during the engine
runs at relatively high speed, both cams 32 and 33 being associated with
the exhaust valves 14 and 15, and a cam 34 associated with the intake
valve 13. Among these five valves, the intake valve 13 which is disposed
at an end of the arrangement of three valves 11, 12, 13 is adapted to be
driven by the cam shaft 23 disposed at the opposite side with respect to
the intake valves. When five valves system including three intake valves
and two exhaust valves is adopted, the intake valve's side tends to have
less space than the exhaust valve's side, since greater number of elements
are positioned at the intake valve's side. Therefore, in the invention,
the intake valve 13 located in less space is adapted to be driven by the
exhaust cam shaft located in larger space.
Below the intake camshaft 22 is disposed a rocker shaft 35 parallel with
the intake camshaft 22, as shown in FIG. 3, which shaft 35 is provided
with swing arms 36, 37, 38, 39 each driven by the cams 28, 29, 30, 31,
while below the exhaust camshaft 23 is disposed a rocker shaft 40 parallel
with the exhaust camshaft 23, as also shown in FIG. 3, which shaft 40 is
provided with swing arms 41, 42, 43 each driven by the cams 32, 33, 34.
Between swinging ends of the swing arms and the upper ends of the valve
stems 17 of the valves 11 to 15 are provided hydraulic lash adjusters
(HLA) 44 for adjusting valve clearances.
With reference to FIG. 4, HLA 44 includes a body 45, a plunger 46 housed in
the body 45, a high pressure chamber 50 in communication with oil
reservoir 47 (see FIG. 1) through a oil passage 48 and a check valve 49, a
check ball 51 comprising the check valve 49, and a plunger spring 52. The
swing arms push the body 45 of HLA 44 when the intake and exhaust valves
open and thereby the plunger 46 is also pushed due to reaction force from
the valve stems 17. Then, high pressure is produced in the high pressure
chamber 50, so that the check ball 51 closes the oil passage 48 with the
result of increasing pressure in the high pressure chamber 50. Thus, since
the oil is not changed in volume, the body cooperates with the plunger 46
to push the intake and exhaust valves down.
After the intake and exhaust valves are closed, the swing arms push the
body 45 of HLA 44 with less force than before and thereby the pressure in
the high pressure chamber 50 decreases. Then, the check ball 51 is pushed
down due to the oil pressure deriving from the oil reservoir 47, so that
the oil is introduced into the high pressure chamber 50. The combination
of the oil pressure and the spring force of the plunger spring 52 forces
the body 45 to contact the swing arm, and also forces the plunger 46 to
contact the valve stem 17, such that the valve clearance is adjusted to be
zero. The oil flowing to the oil reservoir 47 is supplied through an oil
passage 53 extending axially with the rocker shafts 35, 40 and an oil
passage 54 formed in the swing arms.
The valves 11 and 12 among the three intake valves comprise adjustable
valves capable of varying valve timing and valve lift in accordance with
the engine-driven state. The valves 11 and 12 are separately driven by
valve adjusting mechanism.
The remaining valve 13 comprise an unadjustable valve which has constant
valve timing and constant valve lift regardless of the engine-driven
state. The valve 13 is driven by the cam shaft 23 located on the opposite
side to the valve 13.
The exhaust valves 14 and 15 are driven by a common valve adjusting
mechanism.
Since aforementioned all valve adjusting mechanism has identical structure,
only a valve adjusting mechanism 55 is explained hereinbelow.
As illustrated in FIG. 5, the swing arms 36, 37 have extended portions 36a,
37a integrally formed with the swing arms 36, 37 across the rocker shaft
35. These extended portions 36a, 37a have piston chambers 56, 57
respectively, which chambers 56, 57 are arranged to be aligned.
The piston chamber 56 has a first piston 58 and a spring 59 housed therein,
while the piston chamber 57 has a second piston 60 housed therein. The
piston chamber 57 is in communication with the oil passage 53.
When pressurized oil is not supplied to the piston chamber 57, the pistons
58, 60 maintain their positions as shown in FIG. 5 and the intake valve 11
is driven by the swing arm 36 for use during the engine runs at low speed.
On the other hand, when pressurized oil is supplied to the piston chamber
57, the second piston 60 moves to the left as viewed in FIG. 5 to connect
the swing arm 36 with the swing arm 37, with the result that the intake
valve 11 is driven by the swing arm 37 for use during high speed.
In other words, when pressurized oil is not supplied to the piston chamber
57, the cam 28 of the intake cam shaft 22 for use of low speed is selected
to use, with overlapping period T.sub.1 in which both the intake valves
and the exhaust valves open being relatively short, as shown in FIG. 6.
When pressurized oil is supplied to the piston chamber 57, the cam 29 of
the intake cam shaft 22 for use of high speed is selected to use, with
overlapping period T.sub.2 being relatively long, as shown in FIG. 6.
The valve adjusting mechanism 55 is operated in a slant-lined zone shown in
FIG. 7 by selecting a cam for use of high speed, which zone represents
that the engine rotates at high r.p.m and/or the engine has high load. For
this purpose, the oil passage 53 for supplying pressurized oil with the
piston chamber 57 is provided with a solenoid valve 61, as illustrated in
FIG. 8. The solenoid valve 61 is controlled by CPU 70.
CPU 70 receives signals representing engine r.p.m Ne and engine load CE to
thereby control the valve adjusting mechanism 55 via the solenoid valve 61
in accordance with a program stored in ROM 62. RAM 63 stores required
data.
The valve 13 is positioned at an end of three intake valves configuration
to have longer distance L (see FIG. 9) from the center P of the cylinder
bore 1 than the other two intake valves 11 and 12, and comprises a valve
having constant valve timing and valve lift, such that swirl S is
facilitated to create as illustrated in FIG. 9 to increase combustion
speed during low load and low r.p.m. to thereby maintain the combustion in
the engine stable.
Furthermore, the valve 13 has a valve stem having an upper end located to
be closer to the exhaust valves than the other two intake valves 11, 12.
In this embodiment, though both the intake valves 11 and 13 have valve
stems having upper ends located to be closer to the exhaust valves than
the intake valve 12, the valve to be driven by the exhaust cam shaft 23 is
selected to be one which is located to be closest to the exhaust valves
among a plurality of intake valves.
As illustrated in FIG. 1, the intake valves 11 and 12 have different
inclination angles. In this embodiment, the intake valve 11 has 0 degree
of inclination angle with respect to a vertically extending axis passing
the center P of the cylinder bore 1, while the intake valve 12 has 19.5
degrees of inclination angle and the exhaust valves 14 and 15 have about
23 degrees of inclination angles. Thus, larger space can be obtained above
the valve stems of the intake valves 11 and 12 due to the aforementioned
valve arrangement, and thereby the valve adjusting mechanism 55 can be
disposed in that space. A reference numeral 64 represents a plug hole for
inserting a ignition plug thereinto.
It should be noted that those skilled in the art can easily recognize that
this embodiment and thus the present invention can achieve all the
aforementioned objects.
While the present invention has been described in connection with certain
preferred embodiments, it is to be understood that the subject matter
encompassed by way of the present invention is not to be limited to those
specific embodiments. On the contrary, it is intended for the subject
matter of the invention to include all alternatives, modifications and
equivalents as can be included within the spirit and scope of the
following claims.
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